THE RELATIONSHIP BETWEEN UNDRAINED STRENGTH AND PLASTICITY INDEX

The well-known linear correlation between the linear increase in undrained shear strength/effective overburden pressure ratio and the plasticity index in normally consolidated, undisturbed clays is critically examined. The relationship between the undrained shear strength/effective overburden pressure ratio and the plasticity index is studied with the aid of the data available from published literature. The results show marked deviations from the correlation proposed by Skempton (1954). An attempt is made to explain the variation of the above ratio with the plasticity index by means of theoretical considerations which relate that ratio to the pore pressure parameter, the coefficient of earth pressure at rest and the effective angle of shearing resistance. Results of isotropically consolidated undrained triaxial compression tests on seven remoulded clays with plasticity index values from 20 to 495% are reported. These results along with other published data, show that the undrained shear strength/effective overburden pressure ratio tends to descrease as the plasticity index increases. A similar trend is obtained from theoretical analysis. The results also bring out the significant influence of the pore pressure parameter on the value of the ratio. Since many factors such as soil structure, stress level and type of testing govern the undrained strength behavior of normally consolidated soils, any attempt to relate the ratio of undrained shear strength to effective overburden pressure with the plasticity index should give a band rather than a unique relationship.

  • Availability:
  • Corporate Authors:

    Southeast Asian Society of Soil Engineering

    P.O. Box 2754
    Bangkok,   Thailand 

    Southeast Asian Society of Civil Engineering

    P.O. Box 2754
    Bangkok,   Thailand 
  • Authors:
    • Sridharan, A
    • Rao, S N
  • Publication Date: 1973-6

Media Info

  • Features: Figures; References;
  • Pagination: p. 41-53
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00262377
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Dec 13 1974 12:00AM